Observed SubObserved Sub-slab to Indoor Airslab to Indoor ... · (SGSL shallow) is 10x indoor air target screening level SGSL shallow = IASL x 10 ... 0.01 0.1-slab Vap AVG = 7.38

Observed Sub-slab to Indoor AirObserved Sub slab to Indoor Air Attenuation Factors (AF) for Industrial and Commercial Buildings

V I t i I C i l d Vapor Intrusion In Commercial and Industrial Buildings23/24 September 2008

Rosemary A McCaffertySenior Risk AssessorSenior Risk AssessorHaley & Aldrich, [email protected]

OutlineOutline

■ Attenuation Factor (AF) ● Definitions

– EPA,

– NYSDOH

■ Sampling Methods● Sub-slab point Installation

■ Industrial / Commercial Building● Case Study Data

■ Factors Influencing AFs

USEPA Screening Levels■ Attenuation factor (AF or alpha) is

defined as:

AF I d i / S ilAF = Indoor air conc. / Soil gas conc. at source

■ Select indoor air target screening level (IASL)(IASL)

■ Shallow (<=5 ft) soil gas screening level (SGSLshallow) is 10x indoor air target screening level

SGSLshallow = IASL x 10

■ Deep (>5 ft) soil gas screening level■ Deep (>5 ft) soil gas screening level (SGSLdeep) is 100x indoor air target level

SGSLdeep = IASL x 100

(H. Dawson, USEPA, 2002)

NYSDOH Decision Matrix

Effective Attenuation Factor ~0.005

Sampling StrategySampling Strategy

Sub slab Samples■ Sub-slab Samples● Semi-permanent Point (AMS GVP Tip)

Sand Pack with Bentonite Seal● Sand Pack with Bentonite Seal

Sampling Methods

■ Field Screening● Soil Vapor● Soil Vapor

– Tedlar Bag

– Evacuated Canister

– PID/ GC-FID

● Ambient Air

● Vacuum Readings– Back-up Cans/Controllers

Sampling StrategySampling Strategy

■ Sampling Time● 8 hr

● Worker Exposure

■ Sample Size● 6 L

Sampling Methods

■ Field Quality AssuranceBl k S l● Blank Samples– Batch Container Certification

● Background Samples● Background Samples– Ambient Air

■ Lab Quality Assurance■ Lab Quality Assurance● Method Blanks

● Lab Duplicates● Lab Duplicates

● LCS/LCSD

* Photo Courtesy of CAS Labs

Sampling MethodsSampling Methods■ Co-located Samples

● Simultaneous Collection● Simultaneous Collection

Background SamplesBackground Samples

■ Inconspicuous Upwind Location

Case Study 1Case Study 1

■ Active Industrial Manufacturing Facility● 6-10 inch Concrete Foundation

● Numerous sub-basements/vaults and sumps

■ Subsurface soil Impacts

■ Groundwater Impacts

■ Biased Sampling● Source Areas

● Office Spaces

Case Study 2Case Study 2

■ Active Manufacturing Facility

■ Low level Groundwater Contamination● Less than 10 ppb cVOC

■ Warehouse space with basementp

■ Sub-slab samples collected less than 5ft from■ Sub slab samples collected less than 5ft from groundwater table.

Case Study 3Case Study 3

■ Former Heavy Industrial Manufacturing Building● Currently used for office space

● 6 -18 inch concrete slab on spread footings

■ Sub-slab soil contamination

■ Limited groundwater impacts

■ Sub-slab samples collected <5 ft from groundwater table.

Sampling LocationsSampling Locations

Case Study 4Case Study 4

■ Retail/Commercial Building● 4-6 “ concrete Slab on grade

■ No Sub-slab soil sources

■ Widespread Groundwater impactsp p

■ Soil vapor samples collected >5 ft from■ Soil vapor samples collected 5 ft from groundwater table

SamplingSampling Locations

Observed Attenuation FactorsObserved Attenuation Factors

Commercial andIndustrial Sites New YorkIndustrial Sites - New York

1

or

0 001

0.01

0.1

-sla

b Va

po

AVG = 7.38 E-02

0.00001

0.0001

0.001

r Air

/Sub

-

0.0000001

0.000001

Indo

o

SummarySummary

■ Factors influencing AFs at industrial SitesSites● Analytical Detection Limits

● Foundation Construction● Foundation Construction

● Facility size and volume

● Source of Impacts● Source of Impacts– Soil/Groundwater

● Soil Vapor Sample● Soil Vapor Sample– Depth to GW

● Ambient Backgroundg

ConclusionsConclusions

■ AFs can range from 1E-07 to 1E-01

■ Facility Construction influences AFs

■ Independent of cVOC detectedp

■ Site Specific AF can be developed to use Sub-slab■ Site Specific AF can be developed to use Sub slab concentrations to predict IA impacts.

Thank YouThank You

■ Questions

■ For more information visit ● www.haleyaldrich.com/viservices

● Denis Conley – Senor Scientist [email protected]